Post-install script with Python setuptools

Note: The solution below only works when installing a source distribution zip or tarball, or installing in editable mode from a source tree. It will not work when installing from a binary wheel (.whl)

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This solution is more transparent:

You will make a few additions to setup.py and there is no need for an extra file.

Also you need to consider two different post-installations; one for development/editable mode and the other one for install mode.

Add these two classes that includes your post-install script to setup.py:

from setuptools import setup
from setuptools.command.develop import develop
from setuptools.command.install import install


class PostDevelopCommand(develop):
    """Post-installation for development mode."""
    def run(self):
        develop.run(self)
        # PUT YOUR POST-INSTALL SCRIPT HERE or CALL A FUNCTION

class PostInstallCommand(install):
    """Post-installation for installation mode."""
    def run(self):
        install.run(self)
        # PUT YOUR POST-INSTALL SCRIPT HERE or CALL A FUNCTION

and insert cmdclass argument to setup() function in setup.py:

setup(
    ...

    cmdclass={
        'develop': PostDevelopCommand,
        'install': PostInstallCommand,
    },

    ...
)

You can even call shell commands during installation, like in this example which does pre-installation preparation:

from setuptools import setup
from setuptools.command.develop import develop
from setuptools.command.install import install
from subprocess import check_call


class PreDevelopCommand(develop):
    """Pre-installation for development mode."""
    def run(self):
        check_call("apt-get install this-package".split())
        develop.run(self)

class PreInstallCommand(install):
    """Pre-installation for installation mode."""
    def run(self):
        check_call("apt-get install this-package".split())
        install.run(self)


setup(
    ...

P.S. there are no any pre-install entry points available on setuptools. Read this discussion if you are wondering why there is none.